[HTB]: rbtree cleanup

Add code to initialize rb tree nodes, and check for double deletion.
This is not a real fix, but I can make it trap sometimes and may
be a bandaid for: http://bugzilla.kernel.org/show_bug.cgi?id=6681

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index a686b9511b054b765c164a1c0d9cb91117bac1c8..bb3ddd4784b1cebfd4668dc15df844b484b36267 100644 (file)
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -366,7 +366,7 @@ static void htb_add_to_wait_tree(struct htb_sched *q,
  * When we are past last key we return NULL.
  * Average complexity is 2 steps per call.
  */
-static void htb_next_rb_node(struct rb_node **n)
+static inline void htb_next_rb_node(struct rb_node **n)
 {
        *n = rb_next(*n);
 }
@@ -388,6 +388,18 @@ static inline void htb_add_class_to_row(struct htb_sched *q,
        }
 }
 
+/* If this triggers, it is a bug in this code, but it need not be fatal */
+static void htb_safe_rb_erase(struct rb_node *rb, struct rb_root *root)
+{
+       if (RB_EMPTY_NODE(rb)) {
+               WARN_ON(1);
+       } else {
+               rb_erase(rb, root);
+               RB_CLEAR_NODE(rb);
+       }
+}
+
+
 /**
  * htb_remove_class_from_row - removes class from its row
  *
@@ -401,10 +413,12 @@ static inline void htb_remove_class_from_row(struct htb_sched *q,
 
        while (mask) {
                int prio = ffz(~mask);
+
                mask &= ~(1 << prio);
                if (q->ptr[cl->level][prio] == cl->node + prio)
                        htb_next_rb_node(q->ptr[cl->level] + prio);
-               rb_erase(cl->node + prio, q->row[cl->level] + prio);
+
+               htb_safe_rb_erase(cl->node + prio, q->row[cl->level] + prio);
                if (!q->row[cl->level][prio].rb_node)
                        m |= 1 << prio;
        }
@@ -472,7 +486,7 @@ static void htb_deactivate_prios(struct htb_sched *q, struct htb_class *cl)
                                p->un.inner.ptr[prio] = NULL;
                        }
 
-                       rb_erase(cl->node + prio, p->un.inner.feed + prio);
+                       htb_safe_rb_erase(cl->node + prio, p->un.inner.feed + prio);
 
                        if (!p->un.inner.feed[prio].rb_node)
                                mask |= 1 << prio;
@@ -739,7 +753,7 @@ static void htb_charge_class(struct htb_sched *q, struct htb_class *cl,
                htb_change_class_mode(q, cl, &diff);
                if (old_mode != cl->cmode) {
                        if (old_mode != HTB_CAN_SEND)
-                               rb_erase(&cl->pq_node, q->wait_pq + cl->level);
+                               htb_safe_rb_erase(&cl->pq_node, q->wait_pq + cl->level);
                        if (cl->cmode != HTB_CAN_SEND)
                                htb_add_to_wait_tree(q, cl, diff);
                }
@@ -782,7 +796,7 @@ static long htb_do_events(struct htb_sched *q, int level)
                if (time_after(cl->pq_key, q->jiffies)) {
                        return cl->pq_key - q->jiffies;
                }
-               rb_erase(p, q->wait_pq + level);
+               htb_safe_rb_erase(p, q->wait_pq + level);
                diff = PSCHED_TDIFF_SAFE(q->now, cl->t_c, (u32) cl->mbuffer);
                htb_change_class_mode(q, cl, &diff);
                if (cl->cmode != HTB_CAN_SEND)
@@ -1279,7 +1293,7 @@ static void htb_destroy_class(struct Qdisc *sch, struct htb_class *cl)
                htb_deactivate(q, cl);
 
        if (cl->cmode != HTB_CAN_SEND)
-               rb_erase(&cl->pq_node, q->wait_pq + cl->level);
+               htb_safe_rb_erase(&cl->pq_node, q->wait_pq + cl->level);
 
        kfree(cl);
 }
@@ -1370,6 +1384,8 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
 
        if (!cl) {              /* new class */
                struct Qdisc *new_q;
+               int prio;
+
                /* check for valid classid */
                if (!classid || TC_H_MAJ(classid ^ sch->handle)
                    || htb_find(classid, sch))
@@ -1389,6 +1405,10 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
                INIT_HLIST_NODE(&cl->hlist);
                INIT_LIST_HEAD(&cl->children);
                INIT_LIST_HEAD(&cl->un.leaf.drop_list);
+               RB_CLEAR_NODE(&cl->pq_node);
+
+               for (prio = 0; prio < TC_HTB_NUMPRIO; prio++)
+                       RB_CLEAR_NODE(&cl->node[prio]);
 
                /* create leaf qdisc early because it uses kmalloc(GFP_KERNEL)
                   so that can't be used inside of sch_tree_lock
@@ -1404,7 +1424,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
 
                        /* remove from evt list because of level change */
                        if (parent->cmode != HTB_CAN_SEND) {
-                               rb_erase(&parent->pq_node, q->wait_pq);
+                               htb_safe_rb_erase(&parent->pq_node, q->wait_pq);
                                parent->cmode = HTB_CAN_SEND;
                        }
                        parent->level = (parent->parent ? parent->parent->level